1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to generating an elemental image, and more particularly, to generating an elemental image used to display a three-dimensional (3D) image in Integral Photography (IP) or Integral Imaging.
2. Description of the Related Art
FIG. 1 is a conceptual diagram of a three-dimensional (3D) image being displayed by using an elemental image in Integral photography (IP) according to the related art.
A related art apparatus for displaying a 3D image using an elemental image in IP includes an elemental image generator 110 and a display unit 120. The elemental image generator 110 includes a photographing device 111 and a lens array 112. The display unit 120 includes a display device 121 and a lens array 122.
The related art apparatus for displaying a 3D image using an elemental image in IP acquires elemental images of an apple 130 using the elemental image generator 110 and displays the elemental images in the display unit 120 in order for a user 150 to view a 3D object 140. An elemental image is a two-dimensional (2D) fundamental image which is located in the back of the lens array 122 as illustrated in FIG. 1 and allows a user to view a 3D object. The elemental image may be generated by using an actual camera and an actual lens array or by using computer graphics.
The elemental image generator 110 generates and stores elemental images that are 2D images obtained by viewing the apple 130 from various directions. The lens array 112 forms the elemental images of the apple 130 using unit lenses composing the lens array 112. The lens array 112 is achieved by two-dimensionally arranging a plurality of unit lenses. The photographing device 111 stores elemental images of an object, which are formed by the lens array 112.
The display unit 120 performs an inverse process of the process performed by the elemental image generator 110. That is, the display unit 120 displays the elemental images generated by the elemental image generator 110 and reproduces a 3D image 140 using the displayed elemental images. The display device 121 displays the elemental images stored in the photographing device 111. The lens array 122 generates the 3D image 140 by integrating the elemental images displayed by the display device 121. The lens array 122 is achieved by two-dimensionally arranging a plurality of unit lenses.
The related art apparatus for displaying a 3D image using an elemental image in IP generates an elemental image by capturing an actual object using a camera or in a Computer-Generated Integral Photography (CGIP) method and displays the generated elemental image on a film or monitor. However, since an object generated by the elemental image generator 110 is shown in an opposite direction of an object displayed by the display unit 120, when the object is displayed, a pseudoscopic effect occurs. The pseudoscopic effect means that since capturing and reproduction are achieved in an opposite direction to each other, the depth of a reproduced 3D image is shown in reverse. Since depth information of an image captured by a camera is reversed compared to that of a three-dimensionally displayed image due to the pseudoscopic effect, when a user views the displayed image, a convex object is viewed as if concave, a concave object is viewed as if convex, and a closer object is viewed as if smaller than a farther object. A convex portion of the right part of the apple 130, which is closer to the lens array 112 and captured through a side part of the lens array 112, is farther from the lens array 112. When images captured through the lens array 112 of the elemental image generator 110 are displayed through the lens array 122 of the display unit 120, since an apple 140 as a displayed 3D image has only a partial image of a convex part of the right of the apple 130, the apple 140 looks concave on one side thereof from a viewpoint of a person viewing from the other side of the lens array 122. This phenomenon is a kind of pseudoscopic effect and is an inevitable phenomenon occurring due to a basic optical principle when a real image of an actual object in front of a lens array is formed on a film.
FIG. 2 is a conceptual diagram for explaining perspective projection according to the related art.
In 3D computer graphics, perspective projection is used to two-dimensionally represent 3D data. The perspective projection is a method of displaying a frustum 205 on a projection plane 202 at a larger size, as the frustum 205 viewed from a viewpoint 201 is closer to the viewpoint 201. Thus, the size of an object closer to the viewpoint 201 and the size of an object farther from the viewpoint 201 are differently displayed on the projection plane 202. In this case, a volume of an object to which the perspective projection is applied is called the frustum 205, the closest plane from the viewpoint 201 to the frustum 205 is defined as a front-end plane 203, and the farthest plane is defined as a rear-end plane 204.
However, when a 3D image is displayed as a real image by using an elemental image obtained by the perspective projection, the pseudoscopic effect occurs, and even if the pseudoscopic effect is solved, it requires a large amount of time.